This document describes the files used to configure Apache HTTP
Server.

Main Configuration Filesmod_mimeIfDefineIncludeTypesConfig

Apache HTTP Server is configured by placing directives in plain text
configuration files. The main configuration file is usually called
httpd.conf. The location of this file is set at
compile-time, but may be overridden with the -f
command line flag. In addition, other configuration files may be
added using the Include
directive, and wildcards can be used to include many configuration
files. Any directive may be placed in any of these configuration
files. Changes to the main configuration files are only
recognized by httpd when it is started or restarted.

The server also reads a file containing mime document types;
the filename is set by the TypesConfig directive,
and is mime.types by default.

Syntax of the Configuration Files

httpd configuration files contain one directive per line.
The backslash "\" may be used as the last character on a line
to indicate that the directive continues onto the next line.
There must be no other characters or white space between the
backslash and the end of the line.

Arguments to directives are separated by whitespace. If an
argument contains spaces, you must enclose that argument in quotes.

Directives in the configuration files are case-insensitive,
but arguments to directives are often case sensitive. Lines
that begin with the hash character "#" are considered
comments, and are ignored. Comments may not be
included on the same line as a configuration directive.
White space occurring before a directive is ignored, so
you may indent directives for clarity. Blank lines are also ignored.

The values of variables defined with the Define of or shell environment variables can
be used in configuration file lines using the syntax ${VAR}.
If "VAR" is the name of a valid variable, the value of that variable is
substituted into that spot in the configuration file line, and processing
continues as if that text were found directly in the configuration file.
Variables defined with Define take
precedence over shell environment variables.
If the "VAR" variable is not found, the characters ${VAR}
are left unchanged, and a warning is logged.
Variable names may not contain colon ":" characters, to avoid clashes with
RewriteMap's syntax.

Only shell environment variables defined before the server is started
can be used in expansions. Environment variables defined in the
configuration file itself, for example with SetEnv, take effect too late to be used for
expansions in the configuration file.

The maximum length of a line in normal configuration files, after
variable substitution and joining any continued lines, is approximately
16 MiB. In .htaccess files, the
maximum length is 8190 characters.

You can check your configuration files for syntax errors
without starting the server by using apachectl
configtest or the -t command line
option.

You can use mod_info's -DDUMP_CONFIG to
dump the configuration with all included files and environment
variables resolved and all comments and non-matching
IfDefine and
IfModule sections
removed. However, the output does not reflect the merging or overriding
that may happen for repeated directives.

Modulesmod_soIfModuleLoadModule

httpd is a modular server. This implies that only the most
basic functionality is included in the core server. Extended
features are available through modules which can be loaded
into httpd. By default, a base set of modules is
included in the server at compile-time. If the server is
compiled to use dynamically loaded
modules, then modules can be compiled separately and added at
any time using the LoadModule
directive.
Otherwise, httpd must be recompiled to add or remove modules.
Configuration directives may be included conditional on a
presence of a particular module by enclosing them in an IfModule block. However,
IfModule blocks are not
required, and in some cases may mask the fact that you're missing an
important module.

To see which modules are currently compiled into the server,
you can use the -l command line option. You can also
see what modules are loaded dynamically using the -M
command line option.

Scope of DirectivesDirectoryDirectoryMatchFilesFilesMatchLocationLocationMatchVirtualHost

Directives placed in the main configuration files apply to
the entire server. If you wish to change the configuration for
only a part of the server, you can scope your directives by
placing them in Directory, DirectoryMatch, Files, FilesMatch, Location, and LocationMatch
sections. These sections limit the application of the
directives which they enclose to particular filesystem
locations or URLs. They can also be nested, allowing for very
fine grained configuration.

httpd has the capability to serve many different websites
simultaneously. This is called Virtual
Hosting. Directives can also be scoped by placing them
inside VirtualHost
sections, so that they will only apply to requests for a
particular website.

Although most directives can be placed in any of these
sections, some directives do not make sense in some contexts.
For example, directives controlling process creation can only
be placed in the main server context. To find which directives
can be placed in which sections, check the Context of the
directive. For further information, we provide details on How Directory, Location and Files sections
work.

.htaccess FilesAccessFileNameAllowOverride

httpd allows for decentralized management of configuration
via special files placed inside the web tree. The special files
are usually called .htaccess, but any name can be
specified in the AccessFileName
directive. Directives placed in .htaccess files
apply to the directory where you place the file, and all
sub-directories. The .htaccess files follow the
same syntax as the main configuration files. Since
.htaccess files are read on every request, changes
made in these files take immediate effect.

To find which directives can be placed in
.htaccess files, check the Context of the
directive. The server administrator further controls what
directives may be placed in .htaccess files by
configuring the AllowOverride
directive in the main configuration files.